Don Cooper, who once pitched for the Blue Jays, has died at 70.

The White Sox confirmed his passing, extending condolences to his family, friends, and fans.

"The White Sox send our condolences to the family, friends and fans of Don Cooper, who has passed away at 70," the team wrote. "Forever in our thoughts."

Cooper's real legacy was built almost entirely in Chicago, spending 33 seasons as a coach in the White Sox organization from 1988 through 2020.

That run included 18 full seasons as the club's major-league pitching coach, an extraordinary tenure by any standard in professional sports.

Why his 2005 World Series run stands out

Cooper served as pitching coach for the 2005 White Sox, the team that won the World Series that year.

That staff accomplished something genuinely rare, becoming the first team since the 1928 Yankees to throw four consecutive complete games in a single postseason.

Guiding a pitching staff through that kind of postseason dominance places Cooper among the more accomplished coaches of his era, regardless of how his own playing career is remembered.

His path through baseball connects him to Toronto too, having pitched for the Blue Jays organization before eventually finding his true calling on the coaching side of the game.

For a career spanning decades and multiple roles, from player to one of the most tenured pitching coaches in recent memory, Cooper's impact on the sport reached far beyond any single box score.

The White Sox organization and the players he developed over more than three decades will likely share additional tributes and memories in the days ahead.